This invention relates to a semiconductor package, having a heat sink, which packages an integrated circuit chip and, more particularly, to a multi-chip package which makes it possible to cool a multi-chip module and to a shielding package which makes it possible to shield a multi-chip module from electromagnetic interference.
A conventional multi-chip package has been proposed in a paper contributed to a technical report, Vol. 1985. 7. 15, pages 270-278 under the title of "NIKKEI ELECTRONICS". The conventional multi-chip package comprises a plurality of integrated circuit chips, a ceramic substrate, a heat sink, and a plurality of input/output pads. The integrated circuit chips are mounted on a lower surface of the ceramic substrate. The heat sink is fixed on an upper surface of the ceramic substrate. Each of the integrated circuit chips generates heat which is conducted to the heat sink through the ceramic substrate. The heat conducted from the heat sink dissipates in the air.
Another conventional multi-chip package has been proposed in a paper contributed to a technical report, Vol. 1993. 8, pages 61-63 under the title of "NIKKEI MICRODEVICES". Another conventional multi-chip package comprises microprocessor chip, a ceramic substrate having a cavity section at a lower surface thereof, a plurality of surface mount type packages, and a plurality of input/output pins. The surface mount type packages are mounted on an upper surface of the ceramic substrate. Each of the surface mount type packages includes a static RAM. The microprocessor chip is held in the cavity section. The microprocessor chip generates a heat larger than that which is generated from the static RAMs.
A conventional shielding package has been disclosed in a European Patent Application, Publication Number: 0 340 959. The conventional shielding package comprises a wiring board, a plurality of large scale integrated (LSI) circuit chips, a heat sink, a screw, and a nut. Both LSI circuit chips and a heat sink are mounted on the wiring board. The heat sink is fixed to the wiring board by the screw and the nut. An electromagnetic wave generated from the LSI circuit chips is shielded by the heat sink.
However, the above-mentioned semiconductor package has following problems.
In the above-mentioned another conventional multi-chip package, when the heat sink is fixed on the ceramic substrate so that the heat sink is located just above the microprocessor chip, the cooling efficiency of the surface mount type packages is poor, because the surface mount type package is located at the lee of the heat sink.
To solve the above-mentioned problem, previously, potting has been formed around each of the surface mount type packages so that the heat is conducted to the ceramic substrate. However, in that event, it is difficult to detach the surface mount type packages. When each of the surface mount type packages is modified into a bare chip, similarly, it is difficult to detach the bare chip.
In the above-mentioned conventional shielding package, since the heat sink is fixed to the wiring board by the screw and the nut, a long time is required to detach the heat sink and to attach the heat sink.